Abrasion resistance test procedure of leather

The classification of leather is quite complex. According to the tanning method, it can include chrome tanned leather, vegetable tanned leather, oil tanned leather, aldehyde tanned leather and combined tanned leather. According to the level, there are first layer leather and second layer leather, among which the first layer leather includes full grain leather and shaving leather; the second layer leather includes pig second layer leather and cow second layer leather. In addition to the above classification methods, because there are many types of leather materials, we are generally more accustomed to classifying them according to their types. Mainly divided into natural leather and substitute leather. Natural leather is what we call it“Genuine Leather” Most of them are composed of cowhide, sheepskin, pigskin, miscellaneous skins, shaving leather, etc. Among them, cowhide, sheepskin and pigskin are the three major types of leather used in leather making. Substitute leather is what we call it“fake leather” , is a general term for man-made materials such as PVC and PU. Because synthetic leather or other leather-like products are actually artificially synthesized products from basic chemical raw materials. Judgment method and test method of leather wear resistance: The wear resistance of leather is the wear resistance characteristic of leather. Abrasion of leather is an important cause of leather damage. Although the abrasion fastness of leather has not yet been assessed as a national standard, the abrasion resistance test of leather is still indispensable for evaluating its quality, and it is of great significance for evaluating the wearing fastness of leather. Judgment method: There are two methods for judging the leather wear resistance index, namely the end point method and the appearance change method. 1.1 End point method: The number of rotations required to remove 1 mm of leather is the thickness index of wear resistance, and the number of friction rotations is recorded as the wear resistance index. 1.2 Appearance change method: After the test sample has been rubbed for a certain number of times, observe its appearance change, such as color change, degree of wear and other appearance changes as the wear resistance index. Test method 1. Reference standard for flat grinding method: 'GB/T 21196-2007 Determination of abrasion resistance of Martindale fabrics'. Test equipment: There are many types of fabric flat grinders. At present, the Martin denier is the most used in the testing industry, so the flat grind method is often called the MARTINDALE friction tester method. Test principle: The circular sample installed in the sample holder of the Martindale abrasion tester is rubbed against the abrasive (ie, standard fabric) by the plane motion of the Lissajous figure under the specified load. The sample holder can rotate freely about its axis perpendicular to the horizontal plane. The abrasion resistance of the leather is determined according to the total number of frictions in which the sample is damaged. Test method: During the test, the test sample of a certain size is in contact with the standard abrasive under the specified pressure, and the sample is moved relative to the abrasive in the Lissajous trajectory, so that the test sample is uniformly worn in multiple directions. 2. Reference standard of Taber abrasion resistance method: 'GB/T 2726-2005 Determination of Abrasion Resistance of Leather Physical and Mechanical Tests'. Test equipment: TABER abrasion resistance testing machine Test principle: pre-grind for 25 revolutions, place the tested sample on the TABER abrasion resistance testing machine horizontal platform and rotate, two grinding wheels are given a specific pressure to press on the test piece as an option , the axis of the grinding wheel is parallel to the horizontal plane, one grinding wheel is facing outward and the other is facing inward, and all changes in the test piece are recorded within a certain period of time. Test method: A sample with an outer diameter of 108mm and an inner diameter of 8mm was cut with a cutter. Then stick a hard sticker of the same size on the back of the sample. Place the center hole of the sample on the rubber pad of the screw, cover the gasket, and fix the sample with a compression nut. Then put the fixing ring on, and tighten the fixing ring screw with a wrench. Install two H18 grinding wheels on the support arm, each grinding wheel applies 250 to the test sample±10g force, make sure the side with the label is facing outward, make the load of the grinding wheel 500g, connect the vacuum cleaner, connect the vacuum cleaner's suction tube to the connector on the left side of the machine, and start the vacuum cleaner. Set the number of tests according to the standard, and set the rotation speed to 72 rpm. Then start the start button, start the rotation speed to 60±5 times/min of the instrument, rotate horizontally, and perform the test according to the required number of times. During the test, use a brush to remove the attachments on the surface of the sample, observe the wear condition of the test, grind the leather to the specified end point, and record the final number of revolutions. The comparison of test results obtained by testing different materials using the same experimental method is of little significance, but the conclusions drawn from these results are consistent. Therefore, either method can independently quantify the wear resistance of materials. In general, the material of natural leather is softer and therefore less resistant to abrasion. Coated leather has a harder texture and is not easy to wear, so it has better wear resistance.
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